In a multitude of air distribution systems flow limiters are used in order to, starting with an inlet air pressure, cause a desired air volume flow. In the design of an air distribution system a multitude of air lines are connected to a pressure source, and individual flow limiters with different flow resistance parameters adjust the desired air volume flows into the air lines.
Usually, such flow limiters are realised in the form of air line segments in which an aperture plate is integrated through which a certain flow resistance is generated. Because of the abrupt change in cross section, in the region around the aperture opening turbulent flow fields occur which furthermore surround a strongly directional air jet. This results in turbulent flow sound, which in view of the multitude of flow limiters used in complex air distribution systems, for example in vehicles, is perceived by passengers to be a noise nuisance. Moreover, the turbulence level behind an aperture is problematical, because downstream line components, e.g. air outlets, cause more noise with turbulent inflow than with turbulence-free inflow. In order to reduce the noise generated by a conventional flow limiter, usually additional sound absorbers are arranged downstream of the aperture. As a result of this a flow limiter becomes quite heavy and, furthermore, extends further outwards in radial direction than the actual air line so that as a result of this the integration of air lines, for example in vehicles where there is limited installation space, is rendered more difficult.